Geology of the Ban Ban zinc deposit, a sulfide-bearing skarn, Southeast Queensland, Australia

摘要: Skarn lenses at the Ban zinc deposit, Queensland, are conformably enclosed in steeply dipping siliceous metasedimentary rocks, with adjacent metabasaltic rocks and minor limestone. Adamellite intrusives occur nearby. Prograde skarn development is represented by a garnet stage, dominated medium- to coarse-grained grandite (Ad (sub 40-100) ) quartz calcite. Local assemblages rich manganoan hedenbergite near peripheries. The stage crosscut replaced sulfide which, although sphalerite, pyrite, and, lesser extent, magnetite, contain variety of other sulfides, hematite, Ca(-Fe-Mn-Al-Mg) silicates, quartz, Mineralogical metal zonation demonstrated pyrite + or - magnetite assemblage containing low Cu north depth, passing sharply along strike into sphalerite Fe high Zn Cu, Pb, Cd central near-surface areas, which turn grades sulfide, south. A late retrograde chlorite replacement Fe-rich Initial prograde formation may have resulted from reaction between carbonate beds magmatically derived hydrothermal fluids, under generally rather oxidizing conditions. formed after metamorphic peak, reflecting decreasing temperature fluids possible ingress meteoric water. probably indicative continuing retrogression temperature.